enable VM tracing in user code via {.define(nimVmTrace).} (#18244)

* enable VM tracing in user code via  `{.define(nimVmTrace).}`

* add vmutils.vmTrace

* add vmTrace

lib/std/vmutils.nim

@@ -0,0 +1,11 @@
+##[
+Experimental API, subject to change.
+]##
+
+proc vmTrace*(on: bool) {.compileTime.} =
+  runnableExamples:
+    static: vmTrace(true)
+    proc fn =
+      var a = 1
+      vmTrace(false)
+    static: fn()